Electrolytic polishing apparatus



Feb. 28, 1961 T. R. BRUNSON El'AL ELECTROLYTIC POLISHING APPARATUS 2 Sheets-Sheet 1 Filed March 6, 1958 Y N E O MN; mw /w D H in M5 A R m D ML Y0 M NH 0%;

Feb. 28, 1961 T. R. BRUNSON ETAL 2,973,311

ELECTROLYTIC POLISHING APPARATUS Filed March 6, 1958 2 Sheets-Sheet 2 Ail! WW INVENTOR. R. BRUNSON G. DAVIS cln/ ATTORNEY W IO JHHWWII United States Patent C) ELECTROLYTIC Pousrmsr; APPARATUS Thayer R. Brunson and Harold G. Davis, Denver, Colo., assignors to Rocky Mountain Metal Products Co., Denver, Colo, a corporation of Colorado Filed Mar. 6, 1958, Ser. No. 719,609

4 Claims. (Cl. 204-494) This invention relates to an electrolytic polishing instrument for restoring the natural corrosive resistant film and producing a permanent brilliant finish to certain metal articles, such as chrome steel. In particular the instrument is designed for treating brackets, bands and appliances of the type used in the field of orthodontics, but the invention is not to be limited in this regard as the instrument may be used extensively in treating various types of metal products other than precious metals.

For purposes of explanation it will be best to refer to the dental orthodontic field wherein numerous appliances made of stainless chrome steel and the like are employed. The high corrosive resistance of chrome alloy is due to a thin transparent film which forms on the surface of such metal and theoretically the mechanical working, welding, etc. of such material tends to break up the continuity of this protective film, whereupon corrosion is possible. For example, quite often a dentist may use too intense heat when welding light bands and attachments and such may well destroy the continuity of the protective film with the result that corrosion'will set in and cause the attachment to loosen or break away in the patients mouth. In addition it is desirable to have these orthodontic appliances when they are installed of high luster finish and as is well known, prior operations of the dentist in annealing, adapting to the patients mouth and heat treating tend to oxidize the surface of these materials whereby there will be no such luster unless there is polishing. Of course, one can polish and clean such materials by bufling or by a mere wire brush, but for various reasons well known in the field, electrolytic polishers have been found to be much more satisfactory.

Hereinafter reference will be made to passivation, which is the process of restoring the continuity of the previously mentioned protective film to make the metal alloys highly resistant to corrosion and thus tolerant to gum tissues. It is possible to passivate by the known technique of pickling materials in a warm 20 percent solution of nitric acid and while such will restore corrosive resistant qualities, such will not produce a polished finish. For this reason it has been found desirable, particularly in the orthodontic field, to utilize an instrument for electrolytically passivating and polishing.

Such instruments are well known in the -orthodontic field and are commercially available for electrolytic passivating and polishing which is similar to electro-plating, except that the anode and cathode are reversed. When the electrolytic polisher is activated, a microscopic layer of material is removed. This restores the natural corrosive resistant film and also produces a permanent brilliant lasting finish in a matter of seconds.

It is the primary purpose and object of the present invention to provide an electrolytic polishing instrument or apparatus of this general type which has incorporated therein certain improvements found to be particularly useful and desired by the practicing Orthodontists.

It is an object of this invention to provide an instrument housing having top and bottom walls spaced by ice side walls and wherein the top wall is removably positioned on the side walls and arranged to support at least one cup for electrolytically treating the metal objects and wherein there is provided directly beneath the top wall but in spaced relation thereto a shallow trough for receiving any liquid treating material that might be spilled or otherwise enter and damage the component parts ofthe instrument.

A further object is to provide an instrument wherein the top portion thereof is supported in spaced relation from the remaining instrument housing for purposes of air ventilation.

Yet another object is to provide an instrument having a plurality of liquid treating cups or bowls and wherein the liquid treating bowls are removably positioned in the top wall of the instrument and are supported by metal cups sealed to the top wall and extending within and detachably secured to the base of the trough.

Another object is to provide apparatus of the type described wherein the parts that normally need eventual replacing may be readily detached and replaced.

It is also an object of the invention to provide an electrolytic passivating and polishing instrument which is sturdy in construction and which has been designed to be compact and at the same time prevent any damage to the component parts of the instrument by the liquid treating agent through spillage or the like of the latter.

Other objects and advantages of the invention will become apparent by referring to the drawings wherein the preferred embodiment is illustrated and wherein like numerals represent similar parts throughout and wherein:

Figure 1 is a perspective View of the instrument incorporating the teachings of this invention;

Figure 2 is a side elevational view thereof;

Figure 3 is a top or plan view thereof;

Figure 4 is a sectional view taken along the lines 4-4 of Figure 3;

Figure 5 is a sectional view taken along the lines 55 of Figure 3; and

Figure 6 is a top view similar to Figure 3 With the top wall of the housing and associated parts removed.

At the outset it should be stated that electrolytic polishers and passivators of this general type function on the same principle as electro-plating except that the anode and the cathode are reversed. By reversing these poles it is possible to take a very small microscopic layer of the metal off the material which produces a very high polish and restores the natural corrosive resistant film mentioned. Bearing this in mind, only the components of the instrument of this invention generally represented by 1 will be illustrated and explained in detail, it being understood that the various electrical components as well as other mechanical components are included in the usual manner.

Instrument 1 includes a substantially rectangular housing composed of a cast bottom wall, not shown, and east side wall means 2 extending upwardly therefrom in the manner shown in Figures 1 and 2 to provide a hollow interior. The side wall means 2 includes a front panel further identified at 3 having the usual switch 4 for energizing the electrical circuit, the lamp bulb 5 for indicating that the electrical circuit is on or off and the pointer 65 which cooperates with a time dial '7 (having indicia not shown) for controlling the time period of the application of the voltage and amperage. Considering Figures 5 and 6, there is shown the back side wall further represented at 8 which is substantially coextensive vertically with the remaining side wall means 2. The entire side wall means 2 could be cast as one unit, but as shown in Figure 6 all is cast as one unit with the exception of the front panel 3. Extending between certain of the side wall means 2, further identified by numeral 9, and cast therewith is a portion 10 extending in a vertical plane and a portion 11 ex- 3 tending in a transverse plane. Parts and 11 are cast preferably of aluminum along with side walls 8 and 9 to form adjacent the top of the side walls but interior of the housing 1 a relatively shallow trough T for a purpose which will be hereinafter apparent.

Referring particularly to Figures 2, 5 and 6, at two points bottom wall 11 of trough T has two enlarged downwardly extending projections 12 and 13 and within each is provided a square slot area 14 for receiving a square sleeve 15, the latter being held in place in each portion 12 and 13 by suitable screw means and washer means 16 and 17 respectively. Each sleeve is provided with a threaded opening that is closed at its bottom by member 12 or 13 and open at its top to trough T.

Upstanding substantially centrally of trough T and cast with wall 11 is a member 18 which at its top is flush with the common transverse plane of the top surfaces of walls 8, 9 and 10. At predetermined points the top of casting portions 8, 9, 16 and 18 are provided with a threaded bolt 29 having a head 21 which rests on top of these castings and extending upwardly from this head is a stud member 22.

Numeral 25 represents the top of the instrument 1, preferably made of special plastic material resistant to the liquid agent to be described such as a plastic known on the market as Insurok. Wall 25 is of substantial thickness and durability and in the bottom surface 26 thereof at various intervals are provided slots 27 for receiving the studs 22 and this is the only means for supporting plate 25 in spaced relation relative to the remainder of the instrument and body. It will be particularly noted that with plate 25 so supported there is an air space 28 between the top wall 25 and the tops of all the various side walls as well as any portions of trough or tray T and thus air from the atmosphere may be readily circulated within the housing 1 to ventilate component parts and prevent over heating.

T he top wall 25 includes two circular openings 36) and 31 spaced from one another and positioned relative to the instrument as shown in Figures 1, 2 and 3. Extending within circular opening 30 and into trough T is a metal cup 32 preferably of Monel metal and depending from the bottom wall 33 of the cup is a solid threaded projection 34 of suitable metal which is threadedly engaged in sleeve 15 of depending portion 12. The top of cup 32 is shaped to form an outwardly extending inverted U-shaped rim 35 to engage a pair of super-imposed O-rings 36. It can be appreciated that once the cup 35 with the O-rings in place is positioned as shown in Figure 5 and rotated to have the stem 34 engage the threads 15, then continued rotation causes the O-rings to be depressed and form a good seal at the top surface of plate 25 and since the cup 32 and portion 34 engage the metal sleeve 15 and in turn the casting, there is an electrical circuit established through each. Positioned Within cup 32 is a solid porcelain cup 38. The other opening 31 likewise receives a similar metal cup 40 having a bottom portion 41 and depending stud 4-2 for threaded engagement in sleeve 15 and there is also provided superimposed O-rings 44 for creating the seal with plate 25 and U-shaped portion 45. In this instance there is provided in and supported by cup 4t) a perforated porcelain cup represented at 46.

Considering Figures 1 to 4 inclusive, there is shown the usual type of dunk r arm 56 having at one end a clip 51 for receiving and supporting the metal being treated and at the other end handle means 52. Extending upwardly from a plate 25 is a member 53 having a downwardly extending stem 54 which passes through opening 55 of plate 25 and therebeneath. Member 53 is of electrically conducting material and is longitudinally split at 56 to form bifurcated portions 57 that may be flexed together or apart somewhat. The main body of member 53, further identified at 58, is separated from the top surface 25 by an insulating washer 59 and a good part of the body 58 is surrounded by cylindrical metal piece 60 for appearance sake and to prevent further outward movement of members 57. Numeral 61 represents crank means having a threaded stem 62 which is received in aligned slots 63 of bifurcated portions 57 and one of these slots is threaded whereby in an obvious manner when the crank 61 is rotated the leaves 57 will be expanded or contracted. Thus the arm 50 may be supported for pivotal adjustment within slot 56 in a manner that should be apparent. Beneath plate 25 stem 54 is surrounded by a pair of washers 65 between which is interposed spring means 66 and electrically conducting lug 67, united with electrical cable C, is connected thereto by bolt means 68 threaded on the lower part of stem 54.

Let us assume that switch S is turned on and that arm 50 is the positive connection to the electrical components of the instrument through cable C and wire lug 67 and that the negative or the minus side are the castings and the cups or bowls 40 and 32. Specifically, the electrical components would include a transformer for reducing input voltage to about 15 volts, a rectifier for converting to D.C., and resistance means to control current. Further, assuming that there is an orthodontic bracket of chrome steel carried by clip 51 and positioned in the liquid treating agent in bowl or cup 46 and that this bowl is supplied with the usual phosphoric acid solution (H PO then an electrical circuit will be established through the acid,and such will passivate and polish the metal of the article. Obviously the perforations in bowl 46 permit the acid to contact bowl or cup 40 to complete the circuit, but bowl 46 prevents the bracket from striking cup 40 and thus shorting the circuit. The preferred acid is phosphoric acid 85 percent syrupy and it should be apparent how the treatment will restore the corrosive resistant film and provide luster. If desired, other well known treating liquids may be utilized and then soda and water to neutralize the acid and more or less wash same 01f may be put in cup 38 and thereafter the same bracket positioned in place therein. A perforated cup may be quite often substituted for cup 38, in which event the treatment would be the same as described in connection with cup 46. All of this type of treating of the articles by the acids and the like is old and bearing this in mind and in View of the foregoing discussion, the operation will be clear.

The advantages of the present machine are in the structural details particularly shown in Figures 5 and 6. It is known that the acid used unavoidably spills and this is very damaging to various parts and furthermore these acids eventually may well spring a leak through the metal cups 32 and 40 and if such should happen there would be decided damage to the inside of the housing which contains the electrical components. To prevent any such damage is the reason tray T is provided as the latter will recover any acid that leaks through the cups 32 and 40 or by the O-ring seals. The tray may be easily wiped free of any such acid and although the instrument is constructed so that acid should not accumulate in tray T, acid invariably does leak beneath bowls 32 and 40 and thus tray or shallow trough T is emergency insurance against damage to the interior components. Also the fact that plate 25 is removably positioned is of importance as on occasion, due to acid spillage, it is desirable to replace plate 25.

Furthermore, the cups 32 and 38 are generally the items that first need replacing and such is a simple matter in view of the fact that they may readily be detached with out disturbing the components beneath tray bottom 11. Also the air space 28 provides a means of circulating air through the electrical components of the machine and such is highly desirable due to the fact that high heat frequently occurs.

From the foregoing description it will be apparent that we have invented an electrolytic polishing apparatus that achieves the objections enumerated and it is clear that its principles may be used for other purposes and in other combinations. Thus, being aware of possible additional modifications and uses, We desire it to be understood that the scope of this invention is not to be limited except in accordance with the terms of the appended claims and equivalents thereof.

What is claimed is:

1. An electrolytic polishing instrument of the type described comprising a substantially closed hollow housing having spaced top and lower walls with side wall means extending therebetween, a liquid impervious shallow trough extending between the side wall means adjacent but spaced from the upper end thereof, said trough being substantially coextensive with the top wall and comprising a solid base substantially parallel with the top wall but spaced therebeneat'n the substantial depth of the trough, at least one opening in said top wall, and a removably positioned cup for liquid supported by said base at said opening to extend from said trough through the opening, the cup being provided with a portion depending from the cup base, said trough base having a projection provided with a sleeve within which said portion is detachably secured.

2. An instrument as defined in claim 1 wherein the part of said cup that passes through the opening terminates in an outwardly directed part, and liquid seal means positioned between said last named part and the upper surface of the top wall.

3. An instrument as defined in claim 2 wherein the top wall is removably secured to said side wall means to provide ready access to the trough base.

4. An instrument as defined in claim 2 wherein the top wall is supported in spaced relation to the upper surface of the side wall means to provide air ventilation to the trough interior.

References Cited in the file of this patent UNITED STATES PATENTS 906,726 Leitch Dec. 15, 1908 1,809,826 Bohlman June 16, 1931 2,491,910 Schinske Dec. 20, 1949 2,532,907 Hangosky Dec. 5, 1950 2,750,332 Miller June 12, 1956 OTHER REFERENCES Chromaster (bulletin), Ward Leonard Electric Co., 4 pages, March 1951. 

1. AN ELECTROLYTIC POLISHING INSTRUMENT OF THE TYPE DESCRIBED COMPRISING A SUBSTANTIALLY CLOSED HOLLOW HOUSING HAVING SPACED TOP AND LOWER WALLS WITH SIDE WALL MEANS EXTENDING THEREBETWEEN, A LIQUID IMPERVIOUS SHALLOW TROUGH EXTENDING BETWEEN THE SIDE WALL MEANS ADJACENT BUT SPACED FROM THE UPPER END THEREOF, SAID TROUGH BEING SUBSTANTIALLY COEXTENSIVE WITH THE TOP WALL AND COMPRISING A SOLID BASE SUBSTANTIALLY PARALLEL WITH THE TOP WALL BUT SPACED THEREBENEATH THE SUBSTANTIAL DEPTH OF THE TROUGH, AT LEAST ONE OPENING IN SAID TOP WALL, AND A REMOVABLY POSITIONED CUP FOR LIQUID SUPPORTED BY SAID BASE AT SAID OPENING TO EXTEND FROM SAID TROUGH THROUGH THE OPENING, THE CUP BEING PROVIDED WITH A PORTION DEPENDING FROM THE CUP BASE, SAID TROUGH BASE HAVING A PROJECTION PROVIDED WITH A SLEEVE WITHIN WHICH SAID PORTION IS DETACHABLY SECURED. 